FEMALE REPRODUCTIVE ANATOMY AND REPRODUCTIVE FUNCTION doc

21 FEMALE REPRODUCTIVE ANATOMY The female reproductive system is composed of the external and internal genitalia. The external genitalia (Fig. 2-1) are collectively termed the pudendum or vulva and are directly visible. The internal genitalia include the vagina, cervix, uterus, uter- ine (fallopian) tubes, and ovaries (Figs. 2-2 and 2-3). Special in- struments are required for inspection of the internal genitalia. Sim- ple specula or other instruments allow direct visualization of the vagina and cervix, but the intraabdominal group can be inspected only by invasive methods (laparotomy, laparoscopy, or culdoscopy) or by sophisticated imaging techniques (ultrasonography, CT scan, or magnetic resonance imaging). EXTERNAL GENITALIA MONS PUBIS (MONS VENERIS) The mons veneris, a rounded pad of fatty tissue overlying the symphysis pubis, develops from the genital tubercle. It is not an organ but a region or a landmark. Coarse, dark hair normally ap- pears over the mons early in puberty. During reproductive life, the pubic hair is abundant, but after the menopause, it becomes sparse. The normal female escutcheon is typically a triangle with the base up, in contrast to the triangle with the base down pat- tern in males. The skin of the mons contains sudoriferous and sebaceous glands. The amount of subcutaneous fat is determined by heredity, age, nutritional factors, and possibly, steroid hormone factors. 2 FEMALE REPRODUCTIVE ANATOMY AND REPRODUCTIVE FUNCTION CHAPTER Copyright 2001 The McGraw-Hill Companies. Click Here for Terms of Use. FIGURE 2-1. External female genitalia. BENSON & PERNOLL’S 22 HANDBOOK OF OBSTETRICS AND GYNECOLOGY Innervation The sensory nerves of the mons are the ilioinguinal and gen- itofemoral nerves. Blood and Lymph Supply The mons is supplied by the external pudendal artery and vein. The lymphatics merge with those from other parts of the vulva and from the lower abdomen. The crossed lymphatic circulation of the labia within the mons is clinically important because it permits metasta- tic spread of cancer from one side of the vulva to the inguinal glands of the opposite as well as to the affected side. FIGURE 2-2. Internal female genitalia (superior view). Clinical Importance Dermatitis is common in the pubic area, and it is important to ob- serve closely if infestation with Phthirus pubis (lice, crabs) is sus- pected. Edema can occur secondary to infections, vulvar varicosi- ties, trauma, or carcinomatous infiltration of the lymphatics. Cancer elsewhere in the vulva also can involve the mons. LABIA MAJORA In the adult female, these two raised, rounded, longitudinal folds of skin are the most prominent features of the external genitalia. They are homologous to the male scrotum. They originate from the gen- ital swellings extending posteriorly and dorsally from the genital tubercle. From the perineal body, they extend anteriorly around the labia minora to merge with the mons. The labia normally are closed in nulliparous women but later open progressively with succeeding vaginal deliveries and become thin and atrophic with sparse hair in later life. CHAPTER 2 FEMALE REPRODUCTIVE ANATOMY 23 BENSON & PERNOLL’S 24 HANDBOOK OF OBSTETRICS AND GYNECOLOGY The skin of the lateral surfaces of the labia majora is thick and often pigmented. It is covered with coarse hair similar to that of the mons. The skin of the inner labia majora is thin and contains no hairs. The labia majora are made up of connective and areolar tis- sue, with many sebaceous glands. A thin fascial layer similar to the tunica dartos of the scrotum is present within the labia just below the surface. The round ligament of the uterus passes through the in- guinal canal (canal of Nuck) to end in a fibrous insertion in the an- terior portion of the labia majora. Small and large coiled subcutaneous sweat glands are situated all over the body except beneath mucocutaneous surfaces, that is, the labia minora or vermilion border of the lips. Normally, the fluid secretion of small coiled (eccrine) sweat glands, which have no re- lationship to hairs, has no odor. Large coiled (apocrine) sweat glands that open into hair follicles are found over the mons, the labia majora, and the perineum as well as the axilla. These glands, which begin to secrete an odorous fluid at puberty, are more active during menstruation and pregnancy. The sweat glands are controlled by the sympathetic nervous system. FIGURE 2-3. Internal female genitalia (midsagittal view). Sebaceous glands are associated with and open into hair folli- cles. On the labia minora, where hairs are absent, however, seba- ceous glands open on the surface. At puberty, an oily secretion with a slight odor is produced. The fluid lubricates and protects the skin from irritation by vaginal discharge. Gland secretion is mediated by hormonal and psychic stimuli. The activity of the sebaceous glands diminishes in older women. Innervation Anteriorly, the labia majora are supplied by the ilioinguinal and pu- dendal nerves. Laterally and posteriorly, they are innervated by the posterior femoral cutaneous nerve. Blood Supply The labia majora are supplied by the internal pudendal artery (de- rived from the anterior parietal division of the internal iliac or hy- pogastric artery) and by the external pudendal artery (from the femoral artery). Drainage is via the internal and external pudendal veins. Clinical Importance The labia majora serve no special function. A cyst of the canal of Nuck often is mistaken for an indirect inguinal hernia. Adher- ence of the labia in infants may indicate vulvitis. External force or the complications of labor can cause vulvar hematoma. Hidrade- nomas are tumors that originate in aprocrine sweat glands, but they become malignant only rarely. Sebaceous cysts, almost invariably benign but often infected, develop from sebaceous glands. LABIA MINORA The labia minora are small, narrow, elongated folds of skin between the labia majora and the vaginal introitus. They are derived from the skin folds beneath the developing clitoris. Normally, the labia minora are in apposition in nulliparas, concealing the introitus. Pos- teriorly, the labia minora merge at the fourchette. The labia are sep- arate from the hymen, the structure marking the vaginal entrance, or introitus. Anteriorly, each labium merges into a median ridge that fuses with its mate to form the clitoral frenulum, an anterior fold that becomes the prepuce of the clitoris. The lateral and anterior surfaces of the labia minora usually are pigmented. Their inner aspect is pink and moist, resembling the vaginal mucosa. The labia minora have neither hair follicles nor sweat glands but are rich in sebaceous glands. CHAPTER 2 FEMALE REPRODUCTIVE ANATOMY 25 BENSON & PERNOLL’S 26 HANDBOOK OF OBSTETRICS AND GYNECOLOGY Innervation and Blood Supply The innervation of the labia minora is via the ilioinguinal, puden- dal, and hemorrhoidal nerves. The labia minora are not truly erec- tile, but a generous vasculature permits marked turgescence with emotional or physical stimulation. They are supplied by the exter- nal and internal pudendal arteries and veins. Clinical Importance The labia minora tend to close the introitus. They increase in size in response to ovarian hormonal stimulation. Indeed, without es- trogen stimulation, they all but disappear. Squamous cell carcinoma of the vulva often originates in the labia, as do sebaceous cysts. The presence of adherent labia minora in the infant is usually due to inflammation. Fusion, however, may indicate sexual maldifferenti- ation. CLITORIS This 2–3 cm long homolog of the penis is found in the midline slightly anterior to the urethral meatus. It is composed of two small, erectile corpora, each attached to the periosteum of the symphysis pubis, and a diminutive structure (glans clitoridis) that is gener- ously supplied with sensory nerve endings. The glans is partially hooded by the labia minora. Innervation and Blood Supply The clitoris is supplied by the hypogastric and pudendal nerves, pelvic sympathetics, and by the internal pudendal artery and vein. Clinical Importance Cancer of the clitoris is rare, but it is extremely serious because of problems of wide extension and early metastases. The inguinal and femoral nodes usually are involved first. VESTIBULE AND URETHRAL MEATUS The triangular area between the labia minora anteriorly onto which the urethra opens, bounded posteriorly by the vaginal orifice, is the vaginal vestibule. It is derived from the urogenital sinus and is cov- ered by delicate stratified squamous epithelium. The urinary meatus is visible as an anteroposterior slit or an inverted V. Like the urethra, it is lined by transitional epithelium. The vascular mucosa of the meatus often pouts or everts. This makes it appear more red than the neighboring squamous vaginal mucosa. Innervation and Blood Supply The vestibule and terminal urethra are supplied by the pudendal nerve and by the internal pudendal artery and vein. Clinical Importance Urethral caruncles, as well as squamous cell or transitional cell car- cinoma, can develop in the urethrovestibular area. PARAURETHRAL GLANDS (SKENE’S GLANDS) Immediately within the urethra, on its posterolateral aspect, are two small orifices leading to the shallow tubular ducts or glands of Skene, which are wolffian duct remnants. The ducts are lined by transitional cells and are the sparse equivalent of the numerous male prostate glands. Innervation and Blood Supply Like the vestibule and urethral meatus, Skene’s glands are supplied by the pudendal nerve and by the internal pudendal artery and vein. Clinical Importance Skene’s glands, which supply minor amounts of mucus, are espe- cially susceptible to gonococcal infection, which may be first evi- dent here. After successful antigonorrheal therapy, nonspecific in- fection with other purulent organisms is common and results in recurrent skenitis. Destruction of the duct using electrocautery or laser may be necessary. PARAVAGINAL OR VULVOVAGINAL GLANDS AND DUCTS (BARTHOLIN’S GLANDS AND DUCTS) AND HYMEN Just external to the hymen are paravaginal, vulvovaginal glands, or Bartholin’s glands, the counterpart of Cowper’s glands in the male. On either side are two tiny apertures. A narrow duct, 1–2 cm long, connects each of these apertures with a small, flattened, mucus- producing gland that lies between the labia minora and vaginal wall. The hymen is a thin, moderately elastic barrier that usually partially but rarely completely occludes the vaginal canal. It is an incomplete double-faced epithelial plate covering a matrix of fibrovascular tissue. Innervation and Blood Supply The hymen and area of the Bartholin’s glands are supplied by the pudendal and inferior hemorrhoidal nerves, arteries, and veins. CHAPTER 2 FEMALE REPRODUCTIVE ANATOMY 27 BENSON & PERNOLL’S 28 HANDBOOK OF OBSTETRICS AND GYNECOLOGY Clinical Importance Bartholinitis can occur with sexually transmitted diseases, espe- cially gonorrhea, and an abscess of Bartholin’s duct can require mar- supialization. A tight hymen can result in painful intercourse (dyspareunia), in which case, hymenotomy or dilatation will be required. The rem- nants of the lacerated hymen following intercourse or delivery are called carunculae hymenales (myrtiformes). Hymenal or perineal scars also can cause dyspareunia. PERINEAL BODY, FOURCHETTE, AND FOSSA NAVICULARIS The perineal body includes the skin and underlying tissues between the anal orifice and the vaginal entrance. The perineal body is sup- ported by the transverse perineal muscle and the lower portions of the bulbocavernosus muscle. The labia minora and majora converge posteriorly to form a low ridge called the fourchette. Between this fold and posterior to the hymen is a shallow depression termed the fossa navicu- laris. Innervation and Blood Supply These structures are supplied by the pudendal and inferior hemor- rhoidal nerves, arteries, and veins. Clinical Importance The perineal body or fourchette often is lacerated during childbirth and can require repair. Because of vascularity, an early or deep epi- siotomy can result in the loss of several hundred milliliters of blood. Faulty repair can be followed by dyspareunia or by reduced sexual satisfaction. INTERNAL GENITALIA VAGINA The vagina (Fig. 2-3) is a thin, muscular, partially collapsed rugose canal 8–10 cm long and about 4 cm in diameter. It extends from the hymen at the urogenital cleft to the cervix and curves upward and posteriorly from the vulva. The cervix protrudes several cen- timeters into the upper vagina to form recesses called the fornices. The posterior fornix is usually deeper than the anterior fornix. The lateral fornices are similar in size. The vaginal dimensions are reduced during the climacteric, and all fornices, especially the lateral ones, become more shallow. The vagina lies between the urinary bladder and the rectum and is supported principally by the transverse cervical ligaments (car- dinal ligaments) and the levator ani muscles. The peritoneum of the posterior cul-de-sac (pouch of Douglas) is closely approximated to the posterior vaginal fornix, a detail of surgical importance. The vagina is lined by stratified squamous epithelium, which is thick and folded transversely in nulliparas. Many of these rugae are lost with repeated vaginal delivery and after the menopause. Nor- mally, no glands are present in the vagina. Innervation and Blood Supply The nerve supply to the vagina is via the pudendal and hemor- rhoidal nerves and the pelvic sympathetic system (Fig. 2-4). The blood supply is from the vaginal artery (a descending branch of the uterine artery) and from the middle hemorrhoidal and internal pu- dendal arteries. It is drained by the pudendal, external hemor- rhoidal, and uterine veins. CHAPTER 2 FEMALE REPRODUCTIVE ANATOMY 29 FIGURE 2-4. Arteries and nerves of female genitalia. BENSON & PERNOLL’S 30 HANDBOOK OF OBSTETRICS AND GYNECOLOGY The lymphatic drainage of the lower vagina is via the superfi- cial inguinal nodes; that of the upper vagina is to the presacral, ex- ternal iliac, and hypogastric nodes. This is important in vulvo- vaginal infections and cancer spread. Clinical Importance Vaginal discharge is common and can be due to local or systemic disorders. Infections of the lower reproductive tract are the most common cause of leukorrhea. Estrogen depletion (senile or atrophic vaginitis) and estrogen or psychic stimulation are other causes. Primary cancer of the vagina is very rare, but secondary spread from cervical cancer is not uncommon. CERVIX The cervix of the nonpregnant uterus (Fig. 2-3) is a conical, mod- erately firm organ about 2–4 cm long and some 2.5 cm in outside diameter, with a central, spindle-shaped canal. About half the length of the cervix is supravaginal and close to the bladder anteriorly. Childbirth lacerations account for most cervical distortions. The external os, which is initially round and only a fraction of a cen- timeter in diameter, may gape and be much longer as a result of these tears. Even in the absence of distortions, however, it is cus- tomary to refer to the cervix as having anterior and posterior lips. The cervix is supported by the uterosacral ligaments and trans- verse cervical ligaments (cardinal ligaments). The intravaginal portion of the cervix is covered by stratified squamous cells, which usually extend to approximately the exter- nal os. The cervical canal is lined by secretory columnar epithe- lium. The juncture of these two epithelia is variable and is subject to continual revision under the influence of infections, hormones, and trauma. The countless crevices that give the cervical canal a honeycombed appearance on transverse section are infoldings of the mucus-secreting membrane. Excluding the epithelial covering and the cervical canal, the cervix is composed of approximately 85% connective tissue and 15% smooth muscle fibers that join the uterine myometrium above. The anatomic structure of the cervix undergoes marked alteration during pregnancy, labor, and delivery. Innervation and Blood Supply Innervation of the cervix is via the second, third, and fourth sacral nerves and the pelvic sympathetic plexus (Fig. 2-4). The right and left cervical artery and vein, major branches of the uterine circula- tion, carry most of the blood to and from the cervix. [...]... lumbar nodes CHAPTER 2 FEMALE REPRODUCTIVE ANATOMY 35 Clinical Importance The principal functions of the ovaries include hormone production and the development of ova for the achievement of pregnancy These functions can be interrupted by many factors The ovaries are a frequent site of benign and malignant ovarian tumors Torsion can occur, leading to vascular insufficiency and necrosis Ovarian infections... floor (Figs 2-6 and 2-7) consists of muscles, ligaments, and fascia arranged in such a manner as to support the pelvic viscera; provide sphincterlike action for the urethra, vagina, and rectum; and permit the passage of a term infant It is composed of the upper and lower pelvic diaphragms and the vesicovaginal and rectovaginal septa, which connect the two diaphragms, the perineal body, and the coccyx... to the pelvis include those of the abdomen, back, buttock, perineum, and upper extremity Because many of the muscles have been functionally detailed in preceding portions of this chapter, Table 2-1 summarizes their nerves and blood supply CHAPTER 2 FEMALE REPRODUCTIVE ANATOMY 41 TABLE 2-1 MOTOR NERVE AND BLOOD SUPPLY TO ABDOMINAL AND PELVIC MUSCLES Muscle Motor Nerve(s) ABDOMINAL External oblique Internal... between the sacrum and ilium and between the sacrum and coccyx The innominate bones have three major sections: ilium, ischium, and pubis The ilium is composed of the upper part (ala or wing) and a lower part (body) that forms the upper part of the acetabulum, uniting with the ischium and pubis Medially, the ala of the ilium presents a smooth concave area that anteriorly is the iliac fossa and posteriorly... is from the iliolumbar, deep circumflex iliac, obturator, and gluteal arteries 38 BENSON & PERNOLL’S HANDBOOK OF OBSTETRICS AND GYNECOLOGY FIGURE 2-8 The bony pelvis (posterior view) The ischium has a body, superior and inferior rami, and a tuberosity The body joins with the ilium and pubis to form the acetabulum The inner surface is smooth and contiguous with the body of the ilium (above), forming...CHAPTER 2 FEMALE REPRODUCTIVE ANATOMY 31 Clinical Importance The red appearing, more friable columnar epithelium over the endocervix is responsible for ectropion and may contribute to postcoital bleeding and infection Additionally, the squamocolumnar junction is the site of Ͼ90% of squamous cell carcinomas of the cervix Cervical cancer is the second most common female genital malignant... estradiol (E2), and a small amount of estriol (E3) On the eighth and ninth days of the cycle, the estrogen level stops rising, and LH and FSH levels begin to fluctuate On about the 14th day, a sudden LH surge triggers rupture of the follicle and ovulation (extrusion of the ovum) Slight bleeding occurs, and the empty follicle soon becomes filled with blood, which clots (hemorrhagic follicle) LH and possibly,... PERNOLL’S HANDBOOK OF OBSTETRICS AND GYNECOLOGY glands become more and more tortuous, with serrations of their walls Secretion of gland cells diminishes There is infiltration by polymorphonuclear neutrophils and monocytes Finally, necrosis and slough ensue If pregnancy occurs, active secretion and edema persist The glands become more feathery and serrated; however, the predecidua is not immediately accentuated... OBSTETRICS AND GYNECOLOGY FIGURE 2-5 Parturition pain pathways Afferent pain impulses from the cervix and uterus are carried by nerves that accompany sympathetic fibers and enter the neuraxis at T10, T11, T12, and L1 Pain pathways from the perineum travel to S2, S3, and S4 via the pudendal nerve (From J.J Bonica, The nature of pain of parturition Clin Obstet Gynecol 1975;2:511.) Innervation and Blood... BENSON & PERNOLL’S HANDBOOK OF OBSTETRICS AND GYNECOLOGY of the superior ramus The inferior ramus joins the inferior ramus of the pubis to form the pubic arch The ischial spine is an important obstetric landmark, being the narrowest portion of the pelvis, and is located along the inferior ramus The sacrospinous ligament is found between the ischial spine and the sacrum The pudendal nerve and vessels pass . sudoriferous and sebaceous glands. The amount of subcutaneous fat is determined by heredity, age, nutritional factors, and possibly, steroid hormone factors. 2 FEMALE REPRODUCTIVE ANATOMY AND REPRODUCTIVE FUNCTION CHAPTER Copyright. follicles nor sweat glands but are rich in sebaceous glands. CHAPTER 2 FEMALE REPRODUCTIVE ANATOMY 25 BENSON & PERNOLL’S 26 HANDBOOK OF OBSTETRICS AND GYNECOLOGY Innervation and Blood Supply The. tissue. Innervation and Blood Supply The hymen and area of the Bartholin’s glands are supplied by the pudendal and inferior hemorrhoidal nerves, arteries, and veins. CHAPTER 2 FEMALE REPRODUCTIVE ANATOMY 27 BENSON